SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03ef3509331796ff1414a5d3b434005ac00d6afa973aa4a8e15e75784feac349' 
  AND token = 'A2FiuICXQwTVt2CVinsVfSkEmroigh7LQ6p1g0N5/A0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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