SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b81dda0fa341328b0a749e16198e6727d3328fb2a5764783f713d59d39f7f83' 
  AND token = 'zJN3xzAV+w4Q+eQADv0MO5/BxCKxaaNriZj0oGryGG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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