SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff30dacce00396d96c5ac7eb44dad9e15913fff1121a8628aa5845fe4b98940a' 
  AND token = 'T74V5+GOAuCDwQ3Nj08TU3HX3mtYTuhpfnv9HIVf/rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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