SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f689541be8d0b1cc6e5a551a0e09823b94b6c76c366b4588eba99173bcab968a' 
  AND token = '7GzsMRKRI8hDyyIkfsFurPcnP5MXkK/7ZpzZ0cELV7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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