SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83ef20d9456b16e497ca20d5f6b2b563deabccafcd16dce1479f10e48a09e80c' 
  AND token = 'FlQSj+wiYrT1U3WHyoqR0HIdSZ5NOoNoBEodPmXRkok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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