SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c976cc74c67348caea69f915698ee6014bb1c08e9b74e4bc9ad5a363878c6c8' 
  AND token = '/3tSiPPkCCrTIg+rClkSyTavPv26akGy/rKsruGHsRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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