SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91e30c529ceaa4e763a21fb871cbeab0cc57fcb69d3c573e279ccbff63767b21' 
  AND token = 'wZMG5jhzgJH0Nt1GXhbyjurWaTT+XDl8mkA686t+vII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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