SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a500d4c0ed019f174851e0d65607d2bb3255f8f4307c200546daa1c21388e96' 
  AND token = 'AYPA/HSi4A/W9EwJKz/rK8/zjhW3ICejYHwmMZGlsU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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