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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6d914be8708f13a19c5b664887cc2d43624e1fe2fc02afc0856b2f83693826f' 
  AND token = 'PX1sD3NzRYQzUClE91hUHMCkUE8WJJuhqCkXlThKV78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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