SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e103f25df106f910a21f75c2a748fc2081ebbd6b6786ee8175315fc265f34da0' 
  AND token = '2TaMDOXNDYoJfuZECNxzSslXklriv8PrHGcZZXGR6Cw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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