SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b2ded8d74eed09c89656ba68b123775ce33574cb78154de5623a7f98cbd1c39' 
  AND token = 'YA5tEW7chXY9RXWbQsSRyIKVHmElSDY82EgDhEq8vuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00077

JSON explain

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