SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42b0f8eefd86a7831d845c326469d5f872077fafe408be16b8f3b98bea47cdfc' 
  AND token = 'MwyUgknSheROoyduwaRubt13O4cZnfzG7yMEPVgMVYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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