SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50f3e606580fa6eeb958df2c7a4c853a894839b25e922aedd5eacd0e1afa5f8d' 
  AND token = 'YclGXXgwVdhNBsnSJSjPMVujdMseqNBBUYUbAqm8Z/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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