SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820d80ed9878128a480c9c9419b96fd383e6514a150e138138c175f66424fb09' 
  AND token = 'Sf8T76UaFmI2r6Fp6kzYgq0qjNwbn5W0uP5eepi19Yw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}