SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7623fa32971230dd80d78371c9e64aaf3ff3f29abbbf444277cf882d035bffb' 
  AND token = 'oKpaLgqNMENM3USP6CIjxhkaJti2fmv7HehYHg4ZNOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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