SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40d6d3ac38de16b64cc9d5b62473642b8f0501ceb63970f0758f57f1ada67b02' 
  AND token = 'PGpKq3ssejBLgv/bnDvTEVW5Jy48DvmnTB1exZmWgo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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