SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8761a551832b81a92389f9b50bd31fcefa8e68b0689565f37e4c27346594555c' 
  AND token = '4KORuuqonq/fFdOahD2XoGMFNXPg+oChSGAiMy/yX+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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