SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b10774517887da7f138b55fa3df64a59c49612e24953ddad86420bd12639939' 
  AND token = 'UrIlTEBrVF28qOrVDEPU+ZmAnoJv487nQ9psFCDxUkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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