SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df176abe9880e73aae6cffdee86fb923828d766246e13a419d7f0dee52adc6d9' 
  AND token = 'oDy/EWhoYtDxceVakBjlT4WRUbNCySAJfjwnLySetvM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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