SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa9f370556b4909459941612ff0d28ea8cf4da1c2d5cc449a6931c5a813fb946' 
  AND token = 'S3WZAcSg6twWiAK65oQI2TRvTV88GGpQYp2dnMKxqfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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