SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdad5b2f629c20b873d5d659adb5c00ce9182238d734649bd924f3f475965544' 
  AND token = 'zplmVW7MtS8rjNM5O1DzaBBGxyIWtKnp/R+kLPCs2CY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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