SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51f79584f4eb7418e21e8d1736c5df1da7829297ecf392fc55612142f16b7b05' 
  AND token = 'g2Kjx3WLHYZ1pyQ20h0dspqTPCGCaLFjhQMt04qtVqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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