SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de5b141f98515094fc5584be5bce7346424ae2b0d56f4657d4a24af4d251a2b7' 
  AND token = 'fXw6CU1jCnFMTu8kgHWIIAjVnI4RKr9M181bcmezdbw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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