SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a97eabf5bb8ef53b2b8044f0815819861d308a6d3a394a82cd4fa4738ce6a72' 
  AND token = '9VdVGMlTirM8chac4Hfe7b4TTubMdR2nlSe8PRDFCyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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