SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b200f20bf29535569cff544d880a0da99e89e905ae7a7d9f20497985ae631f6' 
  AND token = '+d6kmBqaWG0Gitw+GsSuFpoZPum8YluKsyVYQ4/3OQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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