SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96a4ba534ef78d4a5242fb4b00e99b60f0711fcdc2d097a032122bdc4dd203ce' 
  AND token = '0+CYd6i6bnjfoaqUIiN36KbkB2sgRr6IEytZpwnO4Ic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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