SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2ae5e2ed6b672af618d326986f5940490116601098db461dfbd3835a38291a7' 
  AND token = 'LkGhrwE9BIsBiU/cHkH1Bp6PPjDDZqWURPjFLQiR0mw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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