SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '766a42b90de721107e2cd87f0999ab2539217bc44440d52cd24d091eed32403c' 
  AND token = '5eVPf1uELk/P4XrQFt0/jILwCCioDF42TZiu0HzXmVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}