SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '702a356a350e6dad11e64d3f6ceb47a0dc5d708fd18651b07f72e4b38896fa90' 
  AND token = '5xatgwMPYUI/JTrpDhFwgqni9CfcDpFwSXawlEdfjm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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