SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '635d51eb589d1f1561d26207e543a27954b40bbc7b76407ec1e10ed42a5bd533' 
  AND token = 'e7zjofVVtEagx3jV6ximNVurygBaNmBNu9RbyDWehpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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