SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '908f18715dfd293f13c0da1a57d8b377ab9525c7109bc4fad84b6c174fbce877' 
  AND token = 'h8qSMPLNCbtlw9LEQABpQsXQHS3JiYqFkHCK3+xXojE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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