SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39d6d92d48f862ec29cc813ff3d2b8153f983d7a8870e8d4aa5ed6a86014aaa0' 
  AND token = '+Bby0AClsGhtCuTKfkgzRpqPMSGuFwDHeZGcxkEFPqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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