SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6bd558785838bbee2661e3c0286126595173084b9ad1df61a1d228b6a42a572' 
  AND token = 'LVzvFzv7ztCKUFCbFz2Jwe4/IqFjK+Su9VNUPWwxQbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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