SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6e17280b02cbca9457f47009da9e32bbaab15ed2bda5f736035ac75786c8e54' 
  AND token = 'uljvzsk/DcMdlZzomHHkTqA1ARB4PiTAlNqawVCHDkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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