SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8468e0015d6a2d41de7676f6154880a66a864ab22967c9b434123e420b34bd0' 
  AND token = 'i3k50+1E9paEm8s+KBhJDLj6VPFOPvAVhyGC6RabQkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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