SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b2787d1dcb3f14db47f598179187ba1d1f89656ca9cdb8a8e7618a2c0559bc5' 
  AND token = 't23t8UFsBiWe+kRoPwZI3pVuV4UShnr0hgbg2T/JBXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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