SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9de258ffccccb1c94c95fdbcdeef9cf5b5c149e9b8b4c9376a8a33812b54c500' 
  AND token = 'Wtf99+xkJvSBx7viwmlNO4ZKy5RJyCylz4PQwXLVhZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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