SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b92d91dc8829740f70621f7f315f1d3abd923feddbedf2683e8139f1e2067f47' 
  AND token = 'PU4QFSDpPIr/KZm61Sf/H4Fri8i1RrP5SylsB0iSu/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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