SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73d49c55e528cac11896327629bd335ae25e1c2534a6c45a718f5db9b76a403b' 
  AND token = '8Lr+NqAyr+sT4ooGxsgoPMhwcZbRXYgmpJHJ2qNJFKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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