SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28c78c4038a69be5aa059d924022769a80658cc9527646cd927883ea44bc27d5' 
  AND token = '7WAm2T68alDPvP7FR1siCQBvAo6cvC/P3iYdfeyHDO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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