SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26e8f2ece2bdf4a88dee9ceb850ecf834dd821aaee319c5d0ce5e306daf19c97' 
  AND token = 'rSxJu2wtQZgyZwplR9KvwLqKQfwfYN2/82FIj34uHyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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