SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '749492ec0944b719470ee8f8ffc2ebea81cf7201bbaf79e4388fbd02681d2c44' 
  AND token = 'jEZzw6kL6CrPiK1wGLRSwPGmBvP+1ZZJiTKrFCu1LjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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