SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5b6c325015394fda967a1fbc7db2239cacf53ef452bcc6d51c20ea167d4784a' 
  AND token = 'fBYCJj9mHB/vjviA2zC0vp7ugRv5/pwE4sSZaycLvAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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