SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2311f7e558d86a64519119bf252966380abefeb98ac32fe0791db385e00ef39' 
  AND token = 'nAOBCafY3jIZqc+SzGhdF/IzEZ09NEmFQCyF1tS47Hw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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