SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8ad90ae505b8664c616ac1f9d3476b18cfecdee06e18ed2d1922d6243ccd904' 
  AND token = 'nNB3C2Pd05uHNYPykSsISg6D/uAHWr95ROT83c6fhIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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