SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83f7fb1ebe614f4155d06ebfd16c3c4894de5081b7cbd6e583bea1aecfd6d9a0' 
  AND token = '0v0sd/mKQdmeH5f0FBanYxuQkqwoqTgsamwJNyLiqQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}