SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b89b2f67c2df6ed73cc8ae6750c350438cd26c9eadba79ca329d41d99be9ed9c' 
  AND token = 'Fn4kTS4ybiEjDNHxVMFe2Vjhn4RJvHJQP8+ozVvBXTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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