SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6feb7fa1dbd902968b72465b56bdff34b2ddc5b4884cd2043a784a2a63c0ba7d' 
  AND token = '5nYvbYlnduQdclLmWOkyBS7B2cUVU5lwsB49Jjethvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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