SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5986c576e8012628dcc713aaedbd5cfcdd5a67728eb0215d784cc598e2c520aa' 
  AND token = 'cuBKfsfThwDcx4zkn1ukZJLaOfbLO7zB9vvdSTZkJpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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