SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e9ee847906e4a0eff74c92f77223e32b0c6d4b335cc295352becc9b7fb1167d' 
  AND token = 'MDiKSOVf1FhTSN63SOklMYytFfUbvOJn8okTHBCwVus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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