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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c5c858f344bdec3799e16351a57dd6b4066fb6c2ddedc1ab2dd5bbafdbc938b' 
  AND token = '4WZDXL2bSjxDyu2nNWHqd6QeeqMUBZ7rank1vlEbC4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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