SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '576703f8140e5325750ddc49e815d445b41d464e9d6fac84b1ff96089114623c' 
  AND token = '7vZMXx5fM1aBr6w8x/hkOIVuSFjjIv7UxNY93EKDOPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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