SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '409061543d8b89e85100d8d3a857c8ee43a0b1c6775777a5aca1bf764eba2143' 
  AND token = 'hmzZyQM134WFV+ivi0g6obKVy42gx5HjV4wbvBvYAOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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