SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f866d8bfd0db69190f7c0be743b9985e3124ac1cbe0769854e9fc58b47aefd7d' 
  AND token = 'r9tanU2MBWuZ7uYh3m5oFb+GAIJ7meGuIYFcgwFQVSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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