SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '965a23a77de4c2cbfc6a307742107d031e7f94c6d8f256c2d3aee2a5f8b4b897' 
  AND token = 'UjU19fgJ+i2PAU1hwXw/Yunml8VwnVixZe3TrEwGws8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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