SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd3450f16aca86096ebfec4dce20dd0c8ecee533dc3fd665c234124822b39b2c' 
  AND token = 'h6HR/dLu987YIBNWvH1glxyrMwz4JcnymSchBL0svrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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