SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfa86af9ccc789a744902b8176bf878fecb6ff4c0da74645b0f49bd1ff745034' 
  AND token = 'VGqIn1Rmson4XuxEVZzmC/B0RHNMgyIEjgO7KNaJs0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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