SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0997dc9bd5cae93cc2a8a39f85d465adda4207d8856302512d0b30ebd8faf9dd' 
  AND token = '6h/MDyY+AUZJKDGcrgyVE9EjLQdinxw8cFkqRaUqBgQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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