SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48773fddd958a561572c8ddd531ac2b4b8007a29ffcdf1924b4aa27f9fdca585' 
  AND token = '7RGFlsLUmIW3SkYevfZb/020ORgcl/KBuNYj+JL78II=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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