SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92341c6b29e941f0e7757859a319ea332c4806c95e99cf6dcfb9c3b75faa07f8' 
  AND token = 'j4KQJyR+2ipmdsORVOy3Ct2ofFtZw/RZVoknBLwYtI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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