SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6a36fe26d031d0bff369e06d79f6d4261ac278bb2eb8e0a29691864d37889e5' 
  AND token = 'X4U9wB24wZqzql9HjC8YxdeQtBYUEWI2PGliVf/oT5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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