SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c68ecdc5ff0e394476ec8b4ef2576dd496c934b3a93adc187dcc353c2be14071' 
  AND token = 'rz+L41wV0E4Q8j9dUEupHg/AlOS6a8RzvTdRLUMb7k0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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