SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '20f6435bf7c19e92905da5e90b32e16e9846d57814ba4bf837ff2f5cb0363f95' 
  AND token = 'qunlQB3n0ROzljZZylVNg2xxS9fDTT+GYcudLWf3+U4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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