SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e34cdfd98c4ec9eab4bcce69b01648d1e501222ca340339dd91f48728d23a6d' 
  AND token = 'rA5drSg5NtjQR5Upa5Sh4yj4IqkNJ9JbdFtKQRwN0rE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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