SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bc6e3f267447b3a37f69ee4492a551f4bbe6bd08dd4dc1e0ec836c5e1a2e28c' 
  AND token = 'K4B9iOqngZLzvnCf8Ux2ShMe7dA+Y1hjWSfFHvwg/88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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