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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '780b232cf2859517bd25551505b1720d086d1eb84dee9a0ce2bfcfcd70fc3dc0' 
  AND token = '+xYe1BMMAEJgq+rmT2MB1/hwfvE7PB1ouiMM5TNnIsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}