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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4eadfcd21cce4a04230d4c4f6191a857a85bce90f98d979ebdeb648250eff00' 
  AND token = '3nzq/63/lqZ0OvnfnIfPiuSri7ebmsiBAxcPzp73Oxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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