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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9fb95fd837c8ea7a82e344eaf9b51a856f61d7037eb19a6784eda5d09ba82cb' 
  AND token = '4aYsJAmKy5iOGVBpAyH2dWZ8JRYxfp2BjGQ306W6kPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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