SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f82edd2e7795993807ae713126288247d997d7b1684b83788a2745151070c9a9' 
  AND token = 'dHEbbRyn/nFdJCYCV5MqDu/Z5BJRwIMySBH1gsCI2T0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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