SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c46cad123f07cdf681bc8f2a824b734fd8bbc4c10726c10644a5ae0883e9b0a8' 
  AND token = 'rPvUkO6SKHhJFJ8mi/j6QmH3BAJii1I6HeUd9gAWzJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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