SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3e1dc4986f4e3595e1f26f1c45d266d46a85a2151c6a7fd49996d92802857c5' 
  AND token = 'C/uJJqOTjND0wy+yVCaYBJ3Iuc8gM7uC4KySyBVOip0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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