SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0b2ea7b177375caf80f36565c3350c94d1183bc3bdb1b2f76f8916aa0904a5' 
  AND token = 'JVp3NzXluC/LhWEydBuMQdCm9djc3qjG14PQrw5AtD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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