SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '550af9e028684818b6055ff3a9069410caf6373e109ad3fe834ed203be34de6e' 
  AND token = 'bZtWiLfigYbIYpH+zUhSZ3MRPXvdwZLFrnB37vj5Tt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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