SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ac9b8603dadf11cd3d1430722dfaca889aaa85047f5f871a72137057a887ae3' 
  AND token = '+bb4NXybzvsEMGXktFazgDshAN5YxPKIifqbxlYoAR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}