SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '739a6a2f14d9b4facf96133383c414f2c0fc820db444031c9984e74fec958887' 
  AND token = '7oPSH4AUAd8WwYAgnBFR+1S26YexDHhVvr4pd8gT0uo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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