SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7df62d82dc062c42d0246172b8dc7c5eb9969d16d668299bfa69311b0bd0ae08' 
  AND token = 'c0NJVSFBnnysh7osaDelwOw3ovWcyCKZCRZslY8o1qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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