SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '441c5daf885e5688477cabe3c0d51a3e69eac043a6a105403a004eb27e1ff3e7' 
  AND token = '5MUgme5U+n2XZxZoHPpVezY8G3MnCTFppwr2GGoiN9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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