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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fbe3ca3b6fdfe436b31fb1ff7e23ec53922d659538a41e8c4dd02b0b8253029' 
  AND token = 'm6mDwn9NUsBeD1UOe2bl5/+SxwuxmFQJ8ogkSg8qHVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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