SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '544be6f697eaf8e8776663b27c93679c1fd8563af15f8bf2bb6e0a06d040c6b6' 
  AND token = 'gvT2lQP/M94QbR1JP2d2mU+2LPYWj+AiZVNPsjvkiBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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