SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5fc595ed77a0720026a8f6fa25da64309754b83a3f5420f99dab0a5a6b987291' 
  AND token = 'mSL9TOPpa9SUYrENQd8F+2wwLBhqzcJfEdmC9NnsUW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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