SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a78147f146adcb11e2aca336d88e2cc69bd0bdce2922a4ccf31aac21cb9ba234' 
  AND token = 'L7QtQpbbKoNojCy7ysUgLtD2sLocdnDmk9AVPNev21M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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