SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '526aaf54eac94268a63cc18c17b0227dbeec2f11982729ec627a89f866952d6c' 
  AND token = 'n/TVvhzARDsIAAx4diR3g2OF2AsfRkaQWSJr4onhozM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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