SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b7ef42f5030b082192b21b18e581f333617641185d8426bce0fc85da43b2689e' 
  AND token = 'W0gCyjaWl8YFWh8UJ928qI0SFLZxPu9dGfxXp4jk6/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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