SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0e3635642bb25f8302e9f54093d8ad2fc6bcc371441cfda4aa2fc6f76b64f4a' 
  AND token = 'vwiop2KtgcX3zV2UJRUnDO88lse/lZiSIWJYt+J7GfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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