SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4681d37f919a7759c347d06736fe3eef76b2067edaebb6399aebec21fd386f7' 
  AND token = 'CmNtgRhFh1ud8Z2mD6eoV0EPUixhtrpzJkV3FgJ7vhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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