SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9286f00d997564661dd582afa33aeb850d4b6b1f6a54162f7e985674527259bb' 
  AND token = 'JtOSp1ymWYGE4XqsByBkoln7JuwRprpXYlkSKLlRHr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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