SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '915676037a9a6edbbd4537e4d44f43a2c6e01dffb128fcad4166256ecd062af2' 
  AND token = 'supfZ2V48z16ibhA4AUvUR29XewraOCyvtAPY6ysr/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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