SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbefbf39957f7a67952f849b1add4cbb65ac38de6542ea24beedae626862181c' 
  AND token = 'WqXEIDSGYycOAFenEV2x4cCQTN49szEjadZ5o/NlglM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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