SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9803a4897ebd5d2311c8fa31d446a87caab055fb6f3496f651253de90b08eba5' 
  AND token = 'iTYpkYweR8WHmFno7HcWAgKRsP4Ns+zSS4BwK7rvLtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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