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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98b55b9d73e26163bab063a86095a76f2fdbfa9fb0e748c744f6f0f344ae2a19' 
  AND token = 'EmlefOZ7eaOOZdEEdMkmj3deumpJ6Sd0T+gG9QjH560=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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