SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0408ce0418930408bd62c1661c4c044fecf90ad3ca13c01c89c29c67ca66642' 
  AND token = 'fYMwlz25ocv4w44bGoEmSt8b0JSeDxTDT8KLbbvNbpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}