SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6057d77b34eaad073face62767438a82abb0b4cc7663ee5970f3131f974f9407' 
  AND token = 'AzJ/1EXmVsLDnXw+//jcT9RJmYGnldWy3iHhdV7+Eqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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