SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6b603f0b3fafd8502d7d0c894787117fb46bd807eb51410076af2131e4f6f2a' 
  AND token = 'V3TnZWq/vmHKjy9mjFks6it2Dmf6zlBFjRwn/A+Bjmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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