SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a678f4cc517908b18a7dff894e93848f5db1e205accdaf3e6731a03c2a270f9' 
  AND token = '1cwJfY/1FNwDh03XvvnTivVqjj9COweVQF+uMIBE4+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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