SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '239faadc66643387ebcf28d77cfa2184e3cc3df9d2896870cc23ec4f7abc37af' 
  AND token = 'g8dtYrGurmuH4LzcZGLasiPQfg3GKDWfXPMeZ72fVWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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