SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f451c1c21f4cc8de853093433b3941ddd2505ba788383f8d67829a51d3d72c3d' 
  AND token = 'nMzNqauuHawOgTm6IhYytB/KZZzJyPIDJELaPTyANnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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