SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd912e4dceecb9d467c4bd0644f58a0c5001a9dcffd317bc0d2496c42f11d7c30' 
  AND token = 'A/E3w77xhRziBS3rl/xfsPMCse+cbd3IVW45VPakvoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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