SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3435e76a55fb1137012600bd462a0eafc272f7c8fa8787ee43c3f00624cc86b2' 
  AND token = 'VIkJPKw6u9WGD7tg983hklYYvvH2uagHRIKX2Lm0+qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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