SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f18e2a6f9f7bea45b60186d94c1ab1ca7a5dedbf2717e807e79bbd38495905b8' 
  AND token = 'GXsyeik4FVcICy0IhbzF4OzjH0R5J+im4Rc+vLy0aqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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