SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '271c900af47b6da89bcd38b712a8cde4e69764f220fae5ee6a8525da05a293d9' 
  AND token = 'bm+rYCd6B15cVgUfVjgxcSmEePxAuzB5T9uIFUJDW1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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