SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19942c1db7d690c68530b57c384b8ae3f746446aedb88f0f4ee996e1016678b1' 
  AND token = 'zczlF0qtDf+h3xmZgjEAhH5ZSpgKZyqVvFdZ5EkETtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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