SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4398b2758414ccaf49491d9263be938dcec714f9e42b5b8b97a3c89f6cb8756' 
  AND token = '+uY2Xu/fSUBEjQsLL34/8UB4gVQEschBX1Kiu0/3yow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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