SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '996896229bd813968580c3be5cb74c667cdea3473fc955ad2136226f04b046be' 
  AND token = '5/Mc2r+LwxPThA5DISnuSzwa+7glkXU3yhVLUZAOaHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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