SELECT 
  1 
FROM 
  q_lock_keys 
WHERE 
  key_id = '6b6c3fa1ef91e5dff47b051fa0e385e8b3a3d4fc524f3f3ed63fd4721ec971d0' 
  AND token = 'SgTeunvO0WQ26PoOiD3Ixb1GQmmoW+uMMbArmf5UCug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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