SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55b6b687b5f03860ab5d762c9192422a0c264e801fa7ff1a7582c8efd16feb76' 
  AND token = 'OSB+YaDKwMMZsvQ7G/jBIflJyZiySVnfWL1Alr1dFp0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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