SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8039c158090c0fcfb279823fc50e1f580ba1c49f536f6c2c4684aa713b6a9531' 
  AND token = 'LLdOtBeDkYT112XRFGz3dSYKS6B+gOcMdZ0YtK864W4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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