SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9e789441bc4899f3e34606d34c747c1c76e5d5d69128eb50931cb3214271313' 
  AND token = 'MbMq9VQXfZ6/ftWZWVcOPu+tjpG7FnkrK8LW7prpNkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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