SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e9a53ae32b0f3d79d57e1922533074cf48c68d741ff9b2dd555c2341144d79c' 
  AND token = 'isXL83xKUodxxm2YXDRKD8tOmTqSF+QS41J2/v9gbD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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