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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e21669978372d4fc3e79f012ae44b8cb2f67f49c7a6e20328931dd66cc8a4a68' 
  AND token = 'xF3MD8es6W3rKm5ZpHmKnwbnT+NHbV0fsA2niNCNvXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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