SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '203c41d4b958cb626b29dde6de6aad7229e26a5c0268b277fbd24e640a941cf7' 
  AND token = 'BVw3xaWwz89+yJguTzjM+sJqnhwvZp3M+0rIDF75OIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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