SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c53b11d0a2d062850c0d4208779b636460e66619f5b696bcebc0ad711550de2' 
  AND token = 'DEo4y3/n8z8IEIcYyp+aRnwmmtESuMGrzWqNXI6vUFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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